Fremantle face a wait on the fitness of Alex Pearce ahead of tough task travelling to face Sydney in round 16 after their skipper was subbed out of Sunday's win over Gold Coast with an arm injury.

Late in the third quarter, Pearce appeared to hyper-extend his left arm in an awkward fall under Sun Sam Day in a marking contest, and quickly made his way to the boundary.

Pearce was slow to get back on his feet after the incident, and looked to nurse the arm from any movement as he made his way from the ground with club medical staff.

The Palawa man and All-Australian fancy was subbed out for Karl Worner with the Dockers highlighting concern over Pearce's forearm.

Freo held on for a 20-point win lifting themselves to fifth on the ladder, and half a game out of the top four, after a 8-5-1 return from the first half of the year.

They travel to the SCG to face the ladder-leading Swans on Saturday, just seven weeks after their 48-point loss when the two sides met on an emotional day following the loss of former Docker Cam McCarthy.

Speaking after the win over Gold Coast, Dockers coach Justin Longmuir said there was a larger concern about Pearce's arm rather than elbow, which "may be a good sign, maybe not" having not seen a replay of the incident at the time of his comments.

"He's got a sore arm. That's all I can give you at the moment," Longmuir said on Sunday.

"We haven't had an update from the doc. Clearly he was worried about it coming off but I don't think the doc's found anything clear cut. So we'll just have to wait and see how it pulls up and see whether it needs a scan. And I'm unsure of the next step."

Longmuir said a like-for-like best replacement option would make their way into the team if needed, but was unwilling to put a line through their skipper to play Sydney.

"Not ruling Pearcy out..he's tough. Hopefully there's no structural damage, and hopefully (we) get some good news."

An update is yet to come out of the Dockers.